{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,28]],"date-time":"2026-07-28T04:58:27Z","timestamp":1785214707815,"version":"3.55.0"},"reference-count":20,"publisher":"Ovid Technologies (Wolters Kluwer Health)","issue":"4","license":[{"start":{"date-parts":[[2026,7,1]],"date-time":"2026-07-01T00:00:00Z","timestamp":1782864000000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0"}],"content-domain":{"domain":["lww.com","ovid.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background:<\/jats:title>\n                    <jats:p>Chiari I malformation secondary to atlantoaxial instability requires reduction and stabilization. When initial foramen magnum decompression (FMD) is performed without recognition of this instability, subsequent salvage surgery is technically demanding and carries substantial risk.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Objective:<\/jats:title>\n                    <jats:p>The objective of this study was to evaluate the clinical and radiological outcomes of posterior C1\u2013C2 screw-rod salvage surgery in patients with Chiari I malformation and atlantoaxial instability following failed FMD.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Materials and Methods:<\/jats:title>\n                    <jats:p>We retrospectively analyzed 21 consecutive patients with Chiari I malformation and atlantoaxial instability who underwent posterior C1\u2013C2 screw-rod salvage surgery after failed FMD. Atlantoaxial instability was defined by dynamic imaging showing an atlantodental interval (ADI) &gt;3 mm on flexion or vertical odontoid protrusion above Wackenheim\u2019s line (WL). Clinical status was assessed with the Japanese Orthopedic Association (JOA) score. Radiological outcomes were evaluated by ADI, odontoid tip\u2013WL distance, and cervicomedullary angle (CMA) on computed tomography (CT) and magnetic resonance imaging.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results:<\/jats:title>\n                    <jats:p>\n                      The cohort comprised 14 males and 7 females (mean age: 39.33 \u00b1 8.2 years). Screws were successfully placed in all C1 lateral masses and in 40 of 42 C2 pedicles; in the remaining two cases, C2 inferior articular facet screws were used. Postoperative CT showed complete horizontal reduction (ADI &lt;3 mm) in 90.5% and satisfactory vertical reduction in 85.7%. The mean JOA score improved from 9.8 preoperatively to 14.1 at 6-month follow-up (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      &lt; 0.01). The mean CMA increased from 129.1\u00b0 \u00b1 7.8\u00b0 to 148.8\u00b0 \u00b1 4.5\u00b0 (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      &lt; 0.01). Solid bony fusion was achieved in all patients with follow-up imaging; no implant failure or neurological deterioration occurred.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion:<\/jats:title>\n                    <jats:p>Posterior C1\u2013C2 screw-rod salvage surgery is a safe and effective strategy for Chiari I malformation with atlantoaxial instability after failed FMD. This posterior-only technique provides simultaneous reduction, decompression, and stabilization, yielding significant clinical improvement and reliable fusion even in the previously operated, scarred craniocervical field.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.4103\/jcvjs.jcvjs_84_26","type":"journal-article","created":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T12:00:15Z","timestamp":1784894415000},"page":"392-398","update-policy":"https:\/\/doi.org\/10.1097\/lww.0000000000001000","source":"Crossref","is-referenced-by-count":0,"title":["Posterior C1\u2013C2 screw-rod salvage for Chiari I malformation with atlantoaxial instability after failed foramen magnum decompression"],"prefix":"10.4103","volume":"17","author":[{"given":"Shengli","family":"Guo","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, The First Medical Center, Chinese PLA General Hospital, Beijing, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luokai","family":"Huangfu","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, The First Medical Center, Chinese PLA General Hospital, Beijing, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guangyu","family":"Qiao","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, The First Medical Center, Chinese PLA General Hospital, Beijing, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"276","published-online":{"date-parts":[[2026,7,24]]},"reference":[{"key":"R1-20260728","doi-asserted-by":"crossref","first-page":"e668","DOI":"10.1016\/j.wneu.2017.12.137","article-title":"Atlantoaxial fixation for Chiari 1 formation in pediatric age-group patients: Report of treatment in 33 patients","volume":"111","author":"Goel","year":"2018","journal-title":"World Neurosurg"},{"key":"R2-20260728","doi-asserted-by":"crossref","first-page":"e837","DOI":"10.1016\/j.wneu.2020.11.023","article-title":"Is C1-C2 reduction and fixation a good choice in the treatment of recurrent Chiari-like symptoms with syringomyelia?","volume":"146","author":"\u0130\u015ftemen","year":"2021","journal-title":"World Neurosurg"},{"key":"R3-20260728","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1007\/BF01400872","article-title":"Plate and screw fixation for atlanto-axial subluxation","volume":"129","author":"Goel","year":"1994","journal-title":"Acta Neurochir (Wien)"},{"key":"R4-20260728","doi-asserted-by":"crossref","first-page":"1666","DOI":"10.1007\/s00586-014-3409-5","article-title":"Posterior C1-C2 screw and rod instrument for reduction and fixation of basilar invagination with atlantoaxial dislocation","volume":"23","author":"Guo","year":"2014","journal-title":"Eur Spine J"},{"key":"R5-20260728","doi-asserted-by":"crossref","first-page":"116","DOI":"10.3171\/2014.10.SPINE14176","article-title":"Is atlantoaxial instability the cause of Chiari malformation? 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